The field of the disclosure relates generally to aircraft wing and lift surface control, and more specifically, to methods and systems for active lift surface control using integrated aeroelasticity measurements.
Expectations are that future aircraft designs will face increasing pressure to improve fuel efficiency and performance. One effective fuel efficiency technique is accomplished through measurement of wing twist for various phases of an aircraft flight. Specifically, wing twist is measured, and the data used to produce a reduction in drag through design of a more efficient wing.
To that end, integrated systems for measuring wing twist have been developed for flight test purposes and are referred to herein as integrated aeroelasticity measurement systems. Current practice employs the integrated aeroelasticity measurement system in flight testing, using it to measure actual twist and bending of the airframe for selected flight conditions (aircraft speed, altitude, and fuel load and the like) and measurement points on the wing or body. The data is later used to remove uncertainty in the lift/drag ratio computation, leading to an improved wing design and better understanding of actual performance (meaning more confidence in performance guarantees to the customer). After the flight test data is generated, the integrated aeroelasticity measurement system is removed from the aircraft.
Use of control surfaces to adjust wing twist has been demonstrated in flight test, and those skilled in the art will recognize that wing twist varies as a function of altitude, weight, mach and like factors with a direct impact on the lift/drag ratio of aircraft performance.
There have been experimental aircraft and military aircraft that allow active wing control, however, these applications do not utilize an integrated aeroelasticity measurement system. Generally, these active wing control systems were associated with flight stabilization of the vehicle through operation of the vehicle control system.
Existing solutions for improving aircraft performance rely largely on computer simulation and modeling of wing twist when designing a wing. Other data is provided through the collection of wing twist measurements and flight test data that is related to wing twist. These simulation, modeling, and testing solutions do result in an improved overall wing design. However, such improvements are limited, due to the fixed nature of flight testing and computer simulations. In one example, predicted tables (schedules) are based on weight, altitude, mach, and performance predictions at different loads. These tables are used to adjust flight control surfaces to lower wing drag by twisting the wing as needed. While the method provides a potential improvement, the improvements are limited due to a finite set of data points in the predicted tables, and by the limited effectiveness of using flight control surfaces to lower wing drag. That is, use of flight control surfaces to shape the wing for lower drag is limited because these shape changes also induce wake vortexes and changes to wing camber that tend, after a point, to cancel the improvements in drag.